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Ultrafast above-threshold dynamics of the radical anion of a prototypical quinone electron-acceptor

Quinones feature prominently as electron acceptors in nature. Their electron-transfer reactions are often highly exergonic, for which Marcus theory predicts reduced electron-transfer rates because of a free-energy barrier that occurs in the inverted region. However, the electron-transfer kinetics that involve quinones can appear barrierless. Here, we consider the intrinsic properties of the para-benzoquinone radical anion, which serves as the prototypical electron-transfer reaction product involving a quinone-based acceptor. Using time-resolved photoelectron spectroscopy and ab initio calculations, we show that excitation at 400 and 480 nm yields excited states that are unbound with respect to electron loss. These excited states are shown to decay on a sub-40 fs timescale through a series of conical intersections with lower-lying excited states, ultimately to form the ground anionic state and avoid autodetachment. From an isolated electron-acceptor perspective, this ultrafast stabilization mechanism accounts for the ability of para-benzoquinone to capture and retain electrons

his work was funded by the Engineering and Physical Sciences Research Council (EP/D073472/1), the Spanish Ministerio de Ciencia e Innovacion (MICINN) (CTQ2011-26573 and UNGI08-4E-003 from the European Fund for Regional Development) and the Catalan Agencia de Gestio d’Ajuts Universitaris i de Recerca (SGR0528)

© Nature Chemistry, 2013, vol. 5, núm. 8, p. 711-717

Nature Publishing Group

Author: Horke, Daniel A.
Li, Quansong
Blancafort San José, Lluís
Verlet, Jan R. R.
Date: 2013
Abstract: Quinones feature prominently as electron acceptors in nature. Their electron-transfer reactions are often highly exergonic, for which Marcus theory predicts reduced electron-transfer rates because of a free-energy barrier that occurs in the inverted region. However, the electron-transfer kinetics that involve quinones can appear barrierless. Here, we consider the intrinsic properties of the para-benzoquinone radical anion, which serves as the prototypical electron-transfer reaction product involving a quinone-based acceptor. Using time-resolved photoelectron spectroscopy and ab initio calculations, we show that excitation at 400 and 480 nm yields excited states that are unbound with respect to electron loss. These excited states are shown to decay on a sub-40 fs timescale through a series of conical intersections with lower-lying excited states, ultimately to form the ground anionic state and avoid autodetachment. From an isolated electron-acceptor perspective, this ultrafast stabilization mechanism accounts for the ability of para-benzoquinone to capture and retain electrons
his work was funded by the Engineering and Physical Sciences Research Council (EP/D073472/1), the Spanish Ministerio de Ciencia e Innovacion (MICINN) (CTQ2011-26573 and UNGI08-4E-003 from the European Fund for Regional Development) and the Catalan Agencia de Gestio d’Ajuts Universitaris i de Recerca (SGR0528)
Format: application/pdf
ISSN: 1755-4330 (versió paper)
1755-4349 (versió electrònica)
Document access: http://hdl.handle.net/10256/11473
Language: eng
Publisher: Nature Publishing Group
Collection: MICINN/PN 2012-2014/CTQ2011-26573
MEC/2008/UNGI08-4E-003
AGAUR/2009-2014/2009 SGR-528
Reproducció digital del document publicat a: http://dx.doi.org/10.1038/NCHEM.1705
Articles publicats (D-Q)
Is part of: © Nature Chemistry, 2013, vol. 5, núm. 8, p. 711-717
Rights: Tots els drets reservats
Subject: Reaccions químiques
Chemical reactions
Reacció d’oxidació-reducció
Oxidation-reduction reaction
Title: Ultrafast above-threshold dynamics of the radical anion of a prototypical quinone electron-acceptor
Type: info:eu-repo/semantics/article
Repository: DUGiDocs

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